I would be very interested if Canon made a regular 400mm f4. I would expect the price and size to be in the neighborhood of the 300mm f2.8, but probably a bit longer.

I have no interest in a a 400mm f4 DO lens. I'm not even sure that I would pay $2999 for the f4 DO, but I might be willing to pay $7000 for a regular 400mm f4.

I currently have a 200mm f2 and a 2x teleconverter, but the teleconverter degrades the image and slows focus too much for most applications (action, sports) that I would use it for. Another alternative would be the 300mm f2.8 with the 1.4x teleconverter. I expect that combination would work quite well, but I would love to have a native 400mm f4.

DO lenses are more expensive because of the compact and light weight design. I wonder how light this lens will be? I hope it will be at 1+kg. At that weight I would be inclined to take a long hard look at the lens.

This is yet another with their particle in resin technology "DOE anomalous partial dispersion and bonding materials".

They keep churning out patents for lenses using the technology, but have also noted that they can't control the particle dispersion closely enough to make the process practical. The spacing and distribution of the particles is critical to bend the desired wavelengths of light.

Obviously, they believe that they can bring the process to production. If they do, it can reduce the length of lenses by a substantial amount, and potentially improve the IQ of DO lenses.

DO lenses can bend light waves larger amounts than glass and still not be plagued with CA's. The payoff of a successful particle in resin radial dispersion lens elements will be high. And expect the price to be breath taking, at least initially. They might only be able to use one of one hundred or less lens elements produced.

First, I'm sure that, eventually, DO will be everywhere. I can easily imagine even moderate focal length lenses getting the DO treatment to turn them into fast pancakes.

But it's obviously not easy doing it with today's technology.

What's worse...well, anybody willing to blow big bucks on a Great White isn't interested in compromising image quality. The IQ hit the 400 DO takes...well, why bother if the 400 f/5.6 at a stop higher ISO gives better IQ with the same shutter speed for a fraction of the price and the weight?

So, until Canon can get the image quality of a DO lens not only on a par with their other Great Whites but even a step ahead, it's going to continue to be the redheaded stepchild of the imaging world.

But, in the mean time, they've still got to keep making the things and basically not selling them. Doesn't make for a very easy path from here to there.

A 400mm F/5.6 is just too slow, and a 300mm F/4 just doesn't get close enough. A 400mm F/2.8 is just too expensive.

Sigh.

Well it would most certainly be IS. DO or non-DO?

400 F5.6 IS (new lens) would probably be ~$2000. Add a stop which doubles that amount of glass (gross approximation), the cost gets closer to $5000. Add DO technology to get the lens lighter, 50% premium - close to $8000.

I just don't see Canon coming out with this lens unless the IQ is on par with traditional design.